linux-kernel - Re: [RFT PATCH 2/2] Revert "usb: dwc2: Fix probe problem on bcm2835"

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Date:	Tue, 8 Mar 2016 18:49:42 +0100 (CET)
From:	Stefan Wahren <stefan.wahren@...e.com>
To:	Doug Anderson <dianders@...omium.org>
Cc:	Michael Niewoehner <linux@...ewoehner.de>,
	Tao Huang <huangtao@...k-chips.com>,
	Julius Werner <jwerner@...omium.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	John Youn <johnyoun@...opsys.com>,
	Caesar Wang <caesar.upstream@...il.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Felipe Balbi <balbi@...nel.org>,
	Remi Pommarel <repk@...plefau.lt>
Subject: Re: [RFT PATCH 2/2] Revert "usb: dwc2: Fix probe problem on
 bcm2835"

Hi Doug,

> Doug Anderson <dianders@...omium.org> hat am 7. März 2016 um 22:30
> geschrieben:
>
>
> Stefan,
>
> On Mon, Mar 7, 2016 at 10:40 AM, Stefan Wahren <stefan.wahren@...e.com> wrote:
> > Hi Doug,
> >
> >> Douglas Anderson <dianders@...omium.org> hat am 4. März 2016 um 19:23
> >> geschrieben:
> >>
> >>
> >> This reverts commit 192cb07f7928 ("usb: dwc2: Fix probe problem on
> >> bcm2835") now that we've found the root cause. See the change
> >> titled ("usb: dwc2: Add a 10 ms delay to dwc2_core_reset()").
> >
> > adding a delay of 10 ms after a core reset might be a idea, but applying
> > both
> > patches breaks USB support on RPi :-(
> >
> > I'm getting the wrong register values ...
>
> Ugh. :(
>
> Just out of curiosity, if you loop and time long it takes for the
> registers to get to the right state after reset, what do you get?
> AKA, pick:
>
> https://chromium-review.googlesource.com/331260
>
> ...and let me know what it prints out. On my system I see:
>
> [ 1.990743] dwc2 ff540000.usb: Waited 300001 us, 0x04000400 =>
> 0x04000400, 0x02000800 => 0x02000800
> [ 2.119677] dwc2 ff580000.usb: Waited 9997 us, 0x00100400 =>
> 0x04000400, 0x00000000 => 0x02000800

sure, but this will take some time (weekend).

>
> I believe the difference in behavior is because of the two different
> types of USB controllers (one is OTG and the other is host only).
>
>
> -Doug